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tmpfs: security xattr setting on inode creation

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Adds to generic xattr support introduced in Linux 3.0 by implementing
initxattrs callback.  This enables consulting of security attributes from
LSM and EVM when inode is created.

[hughd@google.com: moved under CONFIG_TMPFS_XATTR, with memcpy in shmem_xattr_alloc]
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jarkko Sakkinen 2012-03-21 16:34:05 -07:00 committed by Linus Torvalds
parent 08ab9b10d4
commit 6d9d88d07e
1 changed files with 72 additions and 16 deletions
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88
mm/shmem.c
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@ -1178,6 +1178,12 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_short_symlink_operations;
#ifdef CONFIG_TMPFS_XATTR
static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
#else
#define shmem_initxattrs NULL
#endif
static int
shmem_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
@ -1490,7 +1496,7 @@ shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
if (inode) {
error = security_inode_init_security(inode, dir,
&dentry->d_name,
NULL, NULL);
shmem_initxattrs, NULL);
if (error) {
if (error != -EOPNOTSUPP) {
iput(inode);
@ -1630,7 +1636,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
return -ENOSPC;
error = security_inode_init_security(inode, dir, &dentry->d_name,
NULL, NULL);
shmem_initxattrs, NULL);
if (error) {
if (error != -EOPNOTSUPP) {
iput(inode);
@ -1704,6 +1710,66 @@ static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *co
* filesystem level, though.
*/
/*
* Allocate new xattr and copy in the value; but leave the name to callers.
*/
static struct shmem_xattr *shmem_xattr_alloc(const void *value, size_t size)
{
struct shmem_xattr *new_xattr;
size_t len;
/* wrap around? */
len = sizeof(*new_xattr) + size;
if (len <= sizeof(*new_xattr))
return NULL;
new_xattr = kmalloc(len, GFP_KERNEL);
if (!new_xattr)
return NULL;
new_xattr->size = size;
memcpy(new_xattr->value, value, size);
return new_xattr;
}
/*
* Callback for security_inode_init_security() for acquiring xattrs.
*/
static int shmem_initxattrs(struct inode *inode,
const struct xattr *xattr_array,
void *fs_info)
{
struct shmem_inode_info *info = SHMEM_I(inode);
const struct xattr *xattr;
struct shmem_xattr *new_xattr;
size_t len;
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
new_xattr = shmem_xattr_alloc(xattr->value, xattr->value_len);
if (!new_xattr)
return -ENOMEM;
len = strlen(xattr->name) + 1;
new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
GFP_KERNEL);
if (!new_xattr->name) {
kfree(new_xattr);
return -ENOMEM;
}
memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN);
memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
xattr->name, len);
spin_lock(&info->lock);
list_add(&new_xattr->list, &info->xattr_list);
spin_unlock(&info->lock);
}
return 0;
}
static int shmem_xattr_get(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
@ -1731,24 +1797,17 @@ static int shmem_xattr_get(struct dentry *dentry, const char *name,
return ret;
}
static int shmem_xattr_set(struct dentry *dentry, const char *name,
static int shmem_xattr_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
struct inode *inode = dentry->d_inode;
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_xattr *xattr;
struct shmem_xattr *new_xattr = NULL;
size_t len;
int err = 0;
/* value == NULL means remove */
if (value) {
/* wrap around? */
len = sizeof(*new_xattr) + size;
if (len <= sizeof(*new_xattr))
return -ENOMEM;
new_xattr = kmalloc(len, GFP_KERNEL);
new_xattr = shmem_xattr_alloc(value, size);
if (!new_xattr)
return -ENOMEM;
@ -1757,9 +1816,6 @@ static int shmem_xattr_set(struct dentry *dentry, const char *name,
kfree(new_xattr);
return -ENOMEM;
}
new_xattr->size = size;
memcpy(new_xattr->value, value, size);
}
spin_lock(&info->lock);
@ -1858,7 +1914,7 @@ static int shmem_setxattr(struct dentry *dentry, const char *name,
if (size == 0)
value = ""; /* empty EA, do not remove */
return shmem_xattr_set(dentry, name, value, size, flags);
return shmem_xattr_set(dentry->d_inode, name, value, size, flags);
}
@ -1878,7 +1934,7 @@ static int shmem_removexattr(struct dentry *dentry, const char *name)
if (err)
return err;
return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
return shmem_xattr_set(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
}
static bool xattr_is_trusted(const char *name)